Crop water stress index computation approaches and their sensitivity to soil water dynamics

There is a growing interest of using canopy temperature (Tc) based methods, including crop water stress index (CWSI), for irrigation management. However, different approaches exist to normalize Tc microclimatic conditions, which can influence the accuracy and suitability CWSI scheduling. This study evaluated performance computation their sensitivity changes in soil depletion under levels. were six – two empirical methods developed lower baseline (i.e., CWSI-EB1, CWSI-EB2), either artificial (CWSI-EA) or actual/natural (CWSI-EN) reference surfaces, theoretical differ by how aerodynamic resistances are determined (CWSI-Th1, CWSI-Th2). Stationary infrared thermometers (IRTs) provided continuous calculate CWSI-EB, CWSI-Th, CWSI-EN; whereas mobile IRTs thermal camera one-point-in-time temperatures surfaces CWSI-EA. These measurements all collected from full deficit irrigated rainfed maize plots West Central Nebraska. Day-to-day variations within across evident varied. Greater correlation strength (Dr,i) observed with CWSI-Th CWSI-EB severe Dr,i > 80%) at deeper depths 1.8 2.1 m, producing r2 ranged 0.61 0.80 (slope: 0.03–0.05) 0.69–0.79 0.03–0.04), respectively. Observed differences magnitudes among treatments, warrants specific triggering threshold each approach. Additionally, developing robust coupling both desirable improve management accounting plant status.